Method and apparatus for controlling electrical discharges by means of ultra-violet light



- A. MUTSCHELLER IBTHOD AND APPARATUS FOR CONTROLLING ELECTRICAL DISCHARGES BY MEANS OF ULTRA VIOLET LIGHT Filed May-12, 1920 4 Sheets-Sheet 1 6 Y E "a INVENTOR.

72 U if Morse/#21:

ATTORNEY.

Aug. 17 1926. 1,596,758

A. MUTSCHELLER METHOD AND APPARATUS FOR CONTROLLING ELECTRICAL DISCHARGES BY MEANS OE ULTRA VIOLET LIGHT Filed May 12, 1920 4 Sheets-Sheet 2 igunzE.

=F|guRE E. w

152 i INVENTOR.

fllm/w I/umwmm BY A TTORNEY Aug. 17, 1926. 1,596,758

igunslfi.

A. MUTSCHELLER IBTHOD AND APPARATUS FOR CONTROLLING ELECTRICAL DISCHARGES BY MEANS OF ULTRA 'VIOLET LIGHT Filed May 12, 1920 4 Sh eets-Sheet 4 INVENTOR. ARTHUR Mama/tum BY 2mm A M ATTORNEY P atentetfA ug. 17, 1926.

" unI DY I A nn'rnun iuu'rscnnunn, or NEW 26121:, N. Y.

mrrnon AND AI'IBABATUS Application filed my 12,

y invention relates to vacuum discharge tubes of the kind in which, the discharge of electrons from the cathode is controlled by- .means'of ultra-violet light. 1 5 The method'by-whi h I produce a cathode discharge difi'ers so radically from the methods heretofore used, in the gas-containing X-r' ay and valve tubes, or in the thermoelectric discharge tubes, that some entirely new principles of operation and of operating characteristics are obtained. Thus by merely controllingl the electron discharge from the cathode t ere maypbe obtained either a. valve "tube rectifier for high tension currents, adetector and amplifier of electrical oscillations, or a-newtype of Xray' tube.

In some devices of the prior art ;a dis, charge from the cathode to the anode is effected by means of a comparatively few gas 2 particles left in the tube.' These residual gas particleagive rise, through ionization by impact, to. positive ions.whioh,upon beingattracted to'the cathode, pick up negative charges-and are thenrepelled from the cathode. Again, in an eitreme vacuum. a

1 pure electronic discharge is obtained from a hot surface such as that of a filament In order to thus use theresidual gas left in the tube, -however, it becomes'necessary to control the gas pressure within the tube; "whereas in order to obtaina pure or nearly pure electronic discharge it becomes necessary to free the tube and the electrodes almost entirelyof all'traces of gas. Either of the two conditions just mentioned is ,diflicult to attain, for the simple reason that regulatin ofthe vacuum to an exactdegree is not easy of accomplishment, and there are difliculties in producing and maintaining a 40 very high vacuum in the presence of metallic electrodes; further, a vacuum s6 obtained and answering the requirements practically necessitatesrthe use of certain metals which are expensive and also diflicult'to pre A5 pare.

'Again, in the prior art fonthe pun ose' of focusing the cathode rays from t eir source to the anti-cathode target, within the "gas-containing tube, special devices are required in order to prevent the discharge from striking the glass wall of the tube. Thus in the gas-containing .tube itis diliicult to prevent heating and the accumulation of a charge of static electricity tending tov oppose the flow at current.

non conrnonnme ELECTRICAL mscrrnnens BY mums or uL'rnA-vmm'r LIGHT.

1320. Serial No. 380,896.

In the thermionic discharge tube it is din cult to control theemission of the electrons cated e ectrostatic focusingdevices must. be

employed.

These dlfliculties and: many others are avoided by the use of my invention, in that a discharge is-obtained only from the illuminated surface, without the use-of heat,

which'would otherwise make changes in the discharge.

sired, is illuminated. .For this reason, this surface is the only one emitting the electrons which constitute the discharge.

As asource 0t ultra-violet light I employ any convenient device producing a suflicient intensity of ultra-violet rays, and I place this source either outside ofthe vacuum bulb orjwithin the same, as conditions may require. If the source of ultra-violet light is outside of the vacuum, the rays are admitted through a window made of suitable material I- adjust the source of ultraviolet light in @1101! a way that onlythe ca- =thode side, from which a discharge is deto offer but little resistance to them, and' thus I cause them to irradiate the surface from which a discharge is desired. If the source of the ultra-violet light is inside of the tube, it is located near the cathode to be discharge can be obtained, andthis discharge is proportionate to the intensity of theillumination. A discharge .in the opposite direction,-that is, from the non-llluminated illuminated. By this expedient, coupled anode to the cathode illuminated by ultra yiolet rays, 'does not ordinarily take place.

I regulate the intensity of the ultra-violet light by varying the strength of the current used in producing the ultra-violet light. If desired however, the intensity of the'ult-ra violet light may be varied in any other suit- .able manner.

In employingmy dev ce as WI'BCGIVGI' and amphfierofoscillatio'ns setup 1n wires by electromagnetlcwave act on as 1nw1reless telegra by or telephony, I so arrange the electro es that the grid is either illuminated by ultra-violet light at the same timeLasthe cathode plate, or that no ultra violet rays fall upon it.\ In the case last mentioned, if the grid is not-connected at all it will to a certain extent obstruct the flow of electronic current across'the instrument. This is due to the negative charge accumulating on the 'id'when the latter is exposed to the -bomardment of electrons passing from the-illuminated electrode to the elctrode which is not illuminated. I

However, when the grid .is not connected and ultra-violet rays fall upon it, the grid loses all'negative charge and may assume a positive charge. This is a distinct. advantage. Instead of requiring a potential to be applied from outside of the tube in order to adjust the grid to zero or to confer upon it a slightly positive potential, when the tube is capable'of handling the largest amount of energy, forinstance as an amplifier, and the grid is exposed -to the ultra-violet light, the grid loses all negative charges because of the effects of the ultra-violet rays, and the accumulating positive charges are proportionately neutralized by the negative discharge from the illuminated plate.

only assume a positive charge. Thus there,

is no necessity to employ a second waveirecti 'fier' or valve in order to hold back the nega ,tive half-impulses, and only positive impulses are passed throughthe telephone receiver. The result is, that the receiver diaphragm'to be drawn in one direction only,

the magnetic pull upon the diaphragm being in proportion-to the amplitude of the wave tram. 4

' It is a fact well known in this art that by connecting two audions in series, so that one 'audion acts as a rectifier for. the other, the aggregate effect of the two audions is increased considerably as compared with that 'of a single audion, used alon My instru ment, however, used in single orm, produces an efiect equal to that of the two audions in the relation stated.

In some instances I use stillanother way .of increasing the amplitude ofthecurrent variations; Instead of illuminating'the liegative plate or. the plate and (101111111117 onsly, the illumination can be rendered interinittent'at suitable intervals, so-that the fre- My device, therefore, is self-adjusting to a maximum of quency of the impulses passing into the receiver is such as to cause thereceiver to respond-to a maximum degree. Since it is a fact that most frequencies commonly used in wireless telephony are too high to give good audibility. It is an advantage to be able to receive the waves at frequencies much, lower and such as are best adapted to energize the telephone receiver. As no waves pass through my device, when the plate or the plate and grid are-not illuminated, it follows that the illumination can be interrupted periodically; that is, the oscillation period of the exciting current for the source of ultra violet light can be so adjusted, and the illuminations so varied in consequence, that the oscillation trains, when rectified 'and passed through the telephone receiver, cause the lat-. ter to give the loudest and clearest sounds.

My device, in the, form of anX-ray tube with a curved cathode, ofiers many advantages over the X-ray tubes of -the rior art. Both in the Lilienield and Cooli ge tubes the liberation of electrons is obtained with the aid of one electrode heated to a very high temperature. Particularly, the Coolidge tube operates ly' well and regularly if the vacuum is oft 1e highest degree possible. But when there is a heated filament in the vacuous space, then it is found that small traces of gases in thebulb cause irregularities in the electron emission. The problem of producing and maintaining such a high degree of vacuum requires special metals for the electrodes,'and in general it makes the process of evacuation considerably more dif- In my devicethe cathode is not heated and I find that small traces of gas which jmight not have beenremoved or which might have become set free whilethe tube'is in use, do not cause the same disturbances in the functioning of the tube as -it does in the case of glowin cathode tubes.

The @oolidge tube is based upon the principle that in an extreme vacuum a pure electronic discharge is obtainable from a'heated filament, and this discharge is then focused upon a small area upon the anticathode by 'means of an electrostatic focusing device.

This focusing device consists of a cylinder placed over the filament and which, when charged with a negative potentiahcauses the electrons to, escape through the center of this tube. The'same object" may be attained by placing aspirally shapedjinetallic member, a metallic cylinder or a metallic hemisphere, so arranged as to serve as a shield which, whenv charged, develops an electrostatic force, and this force causes'the electrons to converge and to fall upon a relatively small area, on the anti-cathode.

-. While my improved vacuum tube can be I operated'as either a tube containing a small but appreciable residuum of gas or as contain ing an extremely high vacuum and thus ada ted for a pure electronic discharge, it IS preferably used with an extreme vacuum.

Therefore the vacuum tubes Which I show and describe may be considered as each containing a very high vacuum and as adapted for a pure electronic discharge.

' It may sometimes be advantageous either for radiographic, therapeutic, ic work, not to: allow the entire current phase of the alternating current impulse, either. rectified or non-rectified, .to pass through the tube. This is because the soft rays, which are produced when the low voltage part of the curve passes, is bound to cause injury to the skin, in consequence of the stronger effect of the soft rays upon the skin. With my improved vacuum tube this same object can be accomplished even when the. entire current phase is passed through the tube; or, any desired part of the curve can be prevented from passing through the tube. Thisis done by so producing ultraviolet light as to render the latter intermit tent, so that the ultra-violet rays are produced at the precise moment when it 1s desired that the fraction of the impulse should I pass. This action is similar to that in the audion'tube, as used in accordance with my invention. It is possible also, in the case of X-ray tubes and valve tubes toselect for passage through the tube the particular part of the impulse applied, as may be desired.

This is accomplished by merely causing the ignition current for the source of ultra-v10- let .light to be in synchronism and of proper duration, so as to take placeand to persist at the precise moment, and such moment only, when the impulse should pass.

' .A valuable feature of my type of tube is the absence from it of any electrostatic focusingdevice. The illumination of the inner surface of a uniformly curved cathode of any discharge from the rear of this cathode, and consequently no cathode shield or any other sort offocusing device is necessary to afford,

any desired focal area.

Reference is here made to the fact that the ultra-violet rays are as far as practicable thrown directly upon the cathode, and prevented as far as practicable from falling directly upon the anode;

In many instances I seek to render the ul tra-violet rays as nearly pure as possible that is, free'from the rays of the visible spectrum and from heat rays, as. well as from nondescript rays 0 f other kinds thus rendering the ultra-violet rays pure,

I; seek to intensify their functions, and by so doing to prevent various disturbing effects due to the presence of undesirable rays of other kinds. I particularly wish. to'avoid the use of heat rays; because they tend to elevate the temperature of' the cathode and or. fluoroscop- 4 directly to the metallic surface rendering the tube resistance irregular .as well as inmany other ways interfering with the electric discharge. i I havemade the discovery that under the various conditions above-mentioned, if the ultra-violet rays reach the metallic surface by irradiation, or by reflection, or in such other manner as to greatly reduce the number of'heat rays accompanying them, the action of the ultra-violet rays actually reaching the metallic surface is. rendered more pronounced, more reliable, and by-far more easily controlled than it may be when the rays last-mentioned are allowed to pass from a hot body disposed in close proximity thereto.-

I have made the further discovery that for the discharge electrons, the ultra-violet rays may be rendered very intense and very effective if they are derived from a powerful source of ultra-violet light, located extraneous to the tube but in to.

' 'I have also discovered that the action of the ultra-violet rays may produceexeptionally good effects if the source of the rays be located within the tube, provided the rays when formed are accompanied by a minimum quantity of heat rays, or that after being formed they are by rays.

describe all of the varied forms and uses of my invention, as this would involve an endless amount of detail. However, I will illustrate and describe a few specimens of apparatus in which my invention is incorporated in such manner as to be of advantage in the various arts. 3

Reference is made to the accompanying drawings forming a part of this specification, and in. which indicate like ures.

part throughout the several fig- Figure l is a longitudinal section of a purpose of causing the cathode to.

close proximity therereflection or other: wise, freed in great measure from the heat.

like reference characters vacuum tube used as avalve rectifier, and

shows. one way in which the cathode tcrminalmav be illuminated by ultra-violet'light H reaching it from a source which, while practically located within the vacuum thereof. v

Figure 2 1s a diagram showing how the tube shown in Figure lmay beencrgi-zed by 2nd of a transformer. Figure 3 IS a longitudinal section through a vacuum tube used as a valve rectifier, and

the tube, is not inside shows one way in which thecathode terminal'may be illuminated by ultra-violet light from a source extraneous to the tube," the light in this through a prismoidal' solidbody and being reflected internally thereof.

Figure 4 is .alongitudi'nal section through instance being admitted it vacuum ner of the kenatron,

40 which the'ultra-violet rays 7 Figure I tion valve.

a vacuum tube used as a valve rectifier, and shows anotherway in which the cathode terminal ma be illuminated by ultra-violet light reac ing it through a solid body and 5 by internal reflection within said solid body,

the source of light being extraneous to the tube.

Figure 5 is a longitudinal section through a vacuum tube used as a valve rectifier, the

ultra-violet light being generated within the tube by means of a lamp;

Figure type of mercury 6' is a longitudinal section through located within the vacuum tube.

Figure 7 is a lon itudinal section through a vacuum tube usec i as a valve rectifier, the

ultra-violet lightbeing radiated by an ineandescent filament, and reaching the oathode directly and mainly by reflection.

Figure 8 is a longitudinal section through a vacuum tube useduas an X-ray tube, in

which the ultra-violet rays are thrown upon 25 the cathode by reflection.

.Figure 9 is a diagram of a transformer tube, the ultra-violet rays being generated within the tube or in close proximity thereto, and by ,irradiatign cathode.

transmitted to the Figure 11 I is a longitudinal section through a vacuum tube used after the man-'- the pliotron, the oscillionand various other valve tubes, and in are generated by a miniature mercury lamp vlocated within thetube 12 is a section through a valve tube rovidedwitha grid and adapted-for use in wireless telephony, the'ultra-violet rays in this instance bein generated by a small mercury lamp. locate within the tube.

Figure 13 is a longitudinal section through an oscillation valve,;,' 'whic'hlhe ultra-violet rays are producedlby. avmercuryvapor tube located'within the wall of the 'o'scilla- In the vacuum Figure 1 and embodying-one form of my in vention, the vacuum tube appears at 14 and "is, provided with, a neck portion 15.

This neck portion supports the anode which appears at-16 and has the form of a fiat plate,

5 mounted upon a terminal rod 17. s The cathodeappeais as 18 and has an mately hemispherical form. This approxigives it theadvantage of a large surface, all portions of which are favorably disposed relativelyto the position occupied by the anode.

A terminal wire 19' isconnected with the I cathode,

tube used as an X-ray tube, the ultra-violet light being made by an arc lamp I parts;

bushing in immediate contact therewith.

tube rectifier shown in and the cathode is supported upon posts or lugs 20, carried by the vacuum tube. This vacuum tube is provided with a neck portion 21, and with this neck portion is made of glass. Mounted upon this neck portion 21, and secured thereto by fusion or otherwise, is a tubular member 22, of quartz glass or other material throu h which the ultra-violet light rays can readily pass. The tubular member 22 is referably connected to the neck portion 21 by a joint 23 formed by slightly fusing the abutting edges together.

A pair of metallic conductors, 24 and 25, are provided respectively with portions 26, 27, of suitable form to produce an are when a suitable current is passed through thesethe are thus produced being, of course, located within tubular member 22. The conductors 24, 25, are spaced apart and mounted in position by being securedto a spacing block 28 of insulating material, by means of screws 29 or other appropriate fas tenings. A band 30 of rubber or other appropriate insulating material, serves as a for the conductors 24, 25, and parts The operation of the machinism shown in Figure 1 is, as follows: An are being started and maintained between portions 26, 27, of electrodes 24, 25, the ultra-violet rays from this are pass out through the adjacent wall ofthe tubular member 22 and strike the inher surface ofthe cathode 18. From this cathode 'the electrons are focused directly upon the anode 16mg indicated by broken lines in Figure 1. The portion 27 of the cond-uctor 25 is. enlarged, so as to prevent the" ultra-violet rays and other rays of the are. from passing directly tothe anode 16. Thatis to say, the portion 26serves as a shield for reventing the rays from reaching the ano e. a

In order tmproduc' boththe currents .required for operatin'ghthe arc and the dis-. charges which are to pass between the anode and cathode, I use the mechanism shown diagrammatically in Figure 2.' The conductor 25 is oonnected-toa wire 31 and the conductor 24' is similarly connected to awire- 32. The wires 31 and 32 lead to a secondary trans ormer 34 is provided witha primary winding 38 whereby itis en'ergized. For this purpose the primary winding 38 is connected to wires 39, 40, which'are'energlzed 33 carried by and forming apart I through its primary winding 38, supplies low voltage currents for' the arc and also high potential currents for obtaining a discharge between'the cathode and the anode.

Thus a one-way discharge takes place through the tube 14, but no discharge can take place between the electrodes 24, and

any part located Within the vacuum of the tube 14.

It will be noted here that the source of ultra-violet light, while for all practical purposes located withinthe vacuum tube, is not within the vacuum, and is really extraneous to the vacuum tube, in so far as the action of the device is concerned. The ultraviolet rays which actually reach the cathode are comparatively .pure, and have very little tendency to elevate the temperature of the cathode or of any part immediately adjacent thereto. The ionizing 'action of this form of cathode, operated under the conditions here contemplated, is very great. The result is, that the rectifying action of the vacuum, tube is exceptionally good.

In the form of my device shown in Figure 3, the vacuum tube appears at 41- and is provided with neck portions 42, 43. The neck portion 42carries an inwardly extending reverting portion 42?. The anode appears at 44 and is supported by a conductor 45 which serves as a tube terminal. Mounted withinthe reverting portion 42' of the neck42, is a prismoidal rod 46, made of quartz, and provided with a concave platinized surface 47, thus serving the purpose of an internal reflector. ,The cathode appears at 48, and is made of non-sputtering metal.

It has generally the form of a reflector, and

secured to it isa terminal rod 49. The cathode is supported upon rods one of which shown at 50. Anarc lamp 51 is disposed in axial alinement with the,quart'z rod 46, and is in this instance used as. source of ultra violet rays; These raysv pass--,thr,ough the quartz rod 46-, in the generaltilijiection of the lengththereof, and are reflected by the platinized surface 47 so as to fall upon the cathode 48.

The tube thusdescribedQhas a va1v'ej action, in that discharges taking :placegigbetween the *cathodeand the anode all'pase in a single or unitary direction.

Except as otherwise indicated, theaction of the device shown in Figure 3 is similar to that appearing in-Figrfre 1. In the form shown in Figure 4 the vac uum tube appears at'52, the anode at 53, and the anode terminal at 54.1 Thecathode appears at 55, and has,:'as before, the form of a hemisphere. 'It is. supported upon a cathode terminal rod 56.

The walloftlie vacuum ishprovided with a neck 57 extending internally, and extending throu h this neck is a pris moidal member 58 short rod and made of quartz. This rod has two surfaces 59, 60, the surface 59 being concave and the surface 60 beingconvex.

Thesurface 59 is preferably surfaced with platinum or with some other bright metal so as to render it capable of reflecting-ultra-.

violet rays internally 'of themember. These rays pass out through the surface 60 and strike the cathode. The surface 59 is located in or near-the focus of the reflecting surface 55, so that the ultra-violet rays from the surface 59 are diffused as nearly as-practicable uniformly in relation to the surface 60.

The source of ultra-violet rays is in this instance an arc lamp' 61, which is disposed in axial alinement with the member 58.

This device, like the ones already de scribed, has avalve action, in that the discharges ta-kii place through the tube in a unitary direction. i r 6 Owing to the curvature of the surfaces 59 and 60, the ultra-violet rays upon leaving the member 58 through the surface 60 ar. irradiated so as far as practicable they are projected upon the inner or concave surface of the cathode, but do .not illuminate any other parts, and do not reach the anode.

In the form of my device shown in Figure 5, the vacuum tube appears at 62 and is pro-.

vided with an anode 63, supportedupon an anode terminal 64. In this instance, as in the others above mentioned, the anode has i the form of a flat plate.

The cathode is shown at 65, and. has as before the formof a reflector. It. is made of metal and preferably bright. Connected With-thiscathode is a cathode terminal 66,

aving the form of 2. I

'mating the anode terminal 64 of the tube.

Located within the vacuum tube 62 is 'a mercury lamp 67 havin the general form of a mutilated sphere ma e of quartz and rovided with a flat reflector 68, opaque to tra .violet light. For the purpose of energi ing the lamp 67 I employ a pair of con tors 69,70, havin -in-..this'instance the form of stout insulated wires. These wires are provided with portions 71, 72, which carry small electrodes 73 74, located within the mercury lamp. A vol located .Withinthe lamp, and is. vaporized when a' current is sent throu lamp by aid'of the electrodes 69, .70. current. direcfi alternati'ng or ulsating, depending upon the use -vacuum tube sto be applied. The vacuum tube thus described has 9. rectifying or valve action, and generally speaking may be employed for any purpose requir-ing such a' rectifying'or valve action- Figurefi the vacuum tube at to which I the llC- u'me of liquid mercury 67",

h the'mercur g y 0 and is provided with two necks 76, 77, the .neck 76 having a somewhat reater internal diameter than that of neck 7 in order to serve as a housing for various parts. Lo-

cated within the neck 76 and extending diametrically across the same, is a bridge 78. This bridge supports a pair of electrodes, 79., 80, of such form and so arranged as to be ca able of service'as an arc lamp. A

catho e is shown at 81, and has the form of a concave reflector. It is made as before, of bright metal. Connected with the cathode 81 is a cathode'terminal 82, having the form of a rod. This rod like rods 79 and 80 is secured to the bridge 78 and supported'main- 1y thereby. Connected with the rods 79, 80, '81 are terminal wires 83, 84, 85, the terminal wire 85 being the one in communication with the cathode.- The rods 79 and 80 do not touch the cathode, as they extend through a slot 81 therein.

The anode is shown at 86, and is carried upon an anode terminal rod, 87. Connected with this anode terminal rod isa wire 88, mating the wire'85- and used for supplying high tension current to the tube.

The operation of the device shown in Fig;- ure 6 may readily be understood from the tion of the rod 80, is enlarged so as to serve as a screen and thus prevent the ultra-violet raysof the are from passing directly to the anode.

In the form of my device shown in Fi re 7, the vacuum tube appears at 89 an is provided with two necks 90, 91. The anode is shown at 92, and has in this instance-the form of a flat plate made .of bright metal. It is carried upon a rod 93, extending through the neck 90, and serving as an anode terminal. j

The cathode a pears at 94, and is connected with a r 95, by aid whereof it is supported, and which serves as the cathode terminal of the tube. Located adjacent the cathode, and facing the same, is a metallic member-96 bent to form a concave reflector and supported upon a rod 97. Located adjacent this rod and disposed parallel thereto is "another rod 98. .A filament 99' extends from the rod 98 to the rod 97, this filament being disposed adjacent the member 96 serving ass reflector. The rods' 97. 98 serve as terminals for the filament 99. This filament need not belocated in the ment'of all of these parts issuch that, as

- the reflector are reflected This form of vacuum tube is well reflected strike the cathode.

rincipal focus "of the reflector 96.' The re ative arrangefar as practicable, all ultra-violet rays proceeding from the filament 99 are so reflected as to reach the cathode 94 directly or by reflecti on.

. x In Figure 8, I show a form of my device (.0 in which the invention is applied to'an X- ray tube. A vacuum tube appearsat 100,

and is provided with two necks 101, 102.

The anode appears at 103, and is supported upon a rod 104 serving as the anode termi; 7'

nal- The cathode is shown at 105,.and has the substantially hemispherical above described; .Extending through a hole in the cathode is a small mercury lamp 108, having the general form of a tube and provided 80 with a reflector 109. Encircling the tube just mentioned is a winding 110, and connected with this winding are two wires, 111,. 112, serving as the terminal wires of the mercury lamp 108. The lamp 108 containsa 55 small quantity of mercury and is exhausted,

being thus filled with attenuated mercury vapor. When the lamp is energized by means of the high frequency currents flowing through the winding 110, the vapor be- 9 7 comes luminous, as in the case of other mercury lamps heretofore used. The light emittedby this lamp is rich in ultra-violet rays. The reflector 109 being opaque, none of the ultra-violet rays can pass through it,

and such ultra-violet rays as impinge uponto the left according to Figures 8 and 9, and atthe same time difiused and caused to impinge upon the inner surface of the concave reflector 105, which as above explained is the cathode, andcause it to discharge electrons. V

The X-ray tube just described is energized by either alternating currents or pulsating currents, as the case "may be but in any event, only discharges of unitary d rection can possibly take place through the tube. By means ofthe lamp 108, ultraviolet rays are emitted. These for the most part strike the cathode thence reflected upon the anode. Such of them as strike the reflector 109, are of course reflectedand practically all of the rays-thus The lamp 108 is preferably energized synchronously with the alternations of main discharge terminal.

In Figure 9 I show a transformer and various .other parts especially arranged and ada ted for energizing all parts of the X- ray ube shown 113. of the so-called closedcore type is provided with a primary winding 114 whereby directly and are j potential applied to the in Figure 8. A'transformer it is energized, and connected with this winding are wires 115, 116 through-which alternating. current is supplied. The transformer is provided with a secondary windfrom thelatter a wire 118 leads and 131 lead to and are connected with a. pancake spiral 132. Mating this spiral, and- 'wire 119 leads to the cathode terminal 107-.

count I designate the winding 117 as the main secondary winding of the transformer. Another secondary windin 120 is provided for the transformer, an this secondary winding is by a wire-121 connected with a condenser 122. The secondary winding 120 is by means of another wire 123, connected with another condenser 124. Connected with the condensers 122'and 124 are wires 125, 126 and connected with these wires are two other wires, 127, 128, which leads to a spark gap 129, the latter being'thus bridged across from the wire 125' to the wire 126.

A wire is connected with the wires 125 and 127. Similarly a'wire 131 is connected with the wires 126 and-128' The wires 130 in inductive relation thereto is anotherpane cake spiral 133, the latter being connected to the wires 111, 112 for the purpose of energizin the lamp i108 above described, and with w ich the X-ray tube is provided.-

The winding 120 energizes the condensers 122 and 124; these condensers energize the pancakespiral 132;.this spiral actsinductively upon the pancake spiral 133, and thus within the latter are generated oscillating currents which energize the lamp 108. This lamp thereupon produces ultra-violet rays which strikethe cathode reflector 105.

From here onthe action of the device is similar to that above descr'bed with reference to Figure 8.

In the arrangement shown in Figure 9, likethat appearing in Figure 2, a. single transformer is used to supply current for the main discharge through the X-ray tube,

and also to supply current for energizing the miniature lamp 108, forming virtually a part of the X-ray tube.

In Figure 10, I show still another form of my device and in this form I apply the I principle of my invention to an X-ray tube ofthe so-called Lilicnfeld type. That is to say, the principal is here applied to an X- ray tube of the type illustrated in Figure 1 of patent dated March 6, 19-17, No. 1,218,423,. to J. E.- Lilienfeld'. A vacuum tube 134 is' provided with two necks 135, 136. The anode appars at 137, and is connected with a terminal wire 138. A cathode appears at 139 and has aslight curvature, or in, other words, is sli htly concave. The cathode is provided wit a supportingneck 140. made of metal. Connected with this neck is a terminal wire 141 whichextends out of the tube, through a hollow projection 142. The cathode terminal wire 141 and the anode terminalwire 138.are connected with the end of a secondary winding 143, with which a transformer 144 is provided. Thus the .sec-

ondary winding 143 supplies the potential and current forthe main discharge through the X-ray tube, Located within the neck is a tubulere 145, upon which the sup- L porting neck of the cathode is mounted.

The tubulere 145 is provided with a closed ultra-violet light from the mercury lamp end 144. .A miniature mercury lamp 146 is 146 can pass. The rays of ultra-violet light,

in passing through the openings 1 51 and striking the cathode 139, serve to perform the oftice known in this art as ignition of the tube, for the purpose of controlling the main discharge thereof. 4

Except in the particulars just stated, the

X-ray tube shown in Figure 10 acts like the.

other X-ray tubes above described.

The miniature mercury lamp 146 may be merely an exhaustive capsule, containing a small drop of mercury in a vacuum. The

capsule may be made of quartz, fluorite or other material transparent to ultrai violet rays. It may be cemented or otherwise secured 'in position, but its mountingshould always be such as not to interfere with the maintenance of a suitable vacuumwithin thetube. For purposes of maintaining the instant when the potential between the cath-' vacuum within the tube, the winding 147 should either be fused into position, or

ode and the anode of the X-ray tube is at its maximum. The evacuation ,pfthe tube is of such degree that no discharge whatever can take place within the tube except When the mercury lamp is in" action, and when its action is most interise- Therefore no discharge can takev place through the tube except when the terminals thereof are at their proximate maximum potential. In this way. the X-ray tube as a whole selec tiveiy picks out the peaks and the peaks only of the current waves, the residual portions of the current waves being utterlyunable to pass through the tube. The discharges through the tube are of course, of unitary direction. Y p I In Figure 11 I show my invention as ap plied to a vacuum tube, for use in relation analogous to those of the kenatron, the plioton, the'oscillion, and various othertypes "Ill . in intensity in accordance with sound waves.

The vacuum tube is shown at 152. and contains a positive plate or anode 153 and a negative plate orcathode 154. The cathode 154 is supported upon a rod 155, ending in a terminal 156.. The anode 153 is supported upon a metallic rod 157, ending in a terminal 158. Thus the terminals 156 and 158 are the main terminals. lamp, 159, of the kind'above described, is

mounted'upon a glass stem 160, and extends into a central opening 161 with which the plate 153 is provided. lt'may be connected with any suitable source of alternating current, and for this purpose, is provided with a winding 162 and connected with the ends of'this winding are wires 163, 164, leading to terminals 165. 166.

i The mercury lamp,-159 may be energized. synchronously with the anode 153 and cathode 154 or not, depending upon the particular use for which the device is employed. j

Where the parts just mentioned are energized synchronously, the device canbe used for detecting the presence of electric oscillations of a predetermined frequency. This is done by subjecting both the mercury lamp and the electrodes of the tube, to continuous oscillations of a predetermined frequency. The terminals 1.56 and 158 may be connected with either a telephonic line wire or an antenna to be' energized by the oscillation which are to be selectively picked out or de-.

tectedf Thus when the line wire or the antenna, as the case may .be. is energized by oscillations at the predetermined frequency, and not otherwise,-there are corresponding increases in the current passing through the vacuum tube, which thus respond to the incoming oscillations of the predeterminedfrequency. Again, by varying-the frequency withwhich the device is continuously 'en ergized, and measuring or otherwise noting" the variations of current which pass through the tube, the device can be usedito determine the frequency of oscillations controlled from a'distance. Further. the main terminals 156 and 158 may be subjected to a constant and uniform difference of potential, and the lamp terminals165 and 166 maybe subjected cathode at 184, the cathode bein to potential variations of constant and predetermined frequency, or to potential variations of varying frequencv. as the case may be, the quantity of-current passing throng the tube, being measured or otherwise noted in order to enable the operator to determine when the incoming oscillations have a predetermined frequency or to determine the A miniature mercury frequency of the oscillations thus controlled from a distance. i In addition, the terminals 156 and 158 may ,be subjected to a constant difference of potential and by connecting the terminals 165 and 166 with a sound control microphone, or an aerial, an audion, or the like, variations may be 'set up in the flow of current from the anode 153 to the cathode 154. 'In this manner the device performs the function of an-audion, a pliotr'on, an oscillion a kenatron, or the like, depending upon the particular purpose for which the device is used. I

In the form of my device appearing in Figure 12, the principles just described with reference to Figure 11 may be utilized, but

in Figure 12 I show a grid, in addition to the other parts as hereinafter described.

The vacuum tube is shown at 168, the cathode at 169. the grid at 170, and the anode at 171. The anode is in the form of a plate and is provided with an opening 173. A mercury lamp 174, having the general form of a capsule as above described, extends through this opening. The lamp 174 provided with a winding. 17 5, andconnected with the ends of this winding are stout wires 1-76, .177. The cathode 169 is provided with a terminal 178 and the anode 171 is similarly rovi-ded with a terminal 179. The wires 1 6, 177 are provided with terminals 181, 182.

The device, as a whole, is closely analogous to an audion, a pliotron, an oscillion or the like, which is provided with a grid. The grid-is used in the manner-conventional for devices of this kind. For instance, if the device is used in connection with an aerial for the purpose of receiving wireless communications, the terminal 180 is connected with the aerial.- Except as just dei scribed, the device is similar in its action to the one already described with reference to Figure 11.-

The action of ultra-violet light upon the.

In the form f my device shown in Figme 13, the cathode has the form of a tube terminating in a hemispherical end, and the source of ultra-violet light is an ordinary mercury tube.

The vacuum tube appears at 183, the of the form above described. It is provi edwith an opening 185 and is mounted upon a rod 186 serving as the cathode terminal of the tube. The anode appears at 187, and is a supported upon a metallic the purpose of the anode flat plate of metal rod 188, serving terminal.

Located within the cathode 184, is a ing from my invention, the scope of which mercury vapor tube189, containing a volume 190 of free mercury. The tube 189 1s provided with terminals 191, 192. A wire 193 leads from the terminal 192 through the opening 185 and out through the wall of the tube. A wire 194 is'connected with the terminal 191, and leads therefrom out through the wall of the tube. Thus the wires 193, 194 serve as, terminals for the purpose of energizing the mercury tube 189 and the terminals 186, 188 are the mam terminals of the tube. j

The mercury tube 189 when energized by means of a source of electricity extrinsic to the vacuum tube and suitable for the purpose, throws oif large quantities of ultraviolet rays, which strike the anode 187.

Except as just described the action of the device shown in Figure 13 is similar to that of the other forms of my device.

In each of the various vacuum tubes above described the ain discharge through the tube, from the-sit proportional to the intensity of the ultraviolet rays. The quantity of the discharge therefore depends upon the ultra-violet light, while the penetration of the X-ray depends upon the voltage applied to the terminals of the electrodes. i

The discharge is entirelyvunder the control of the operator,an-d no discharges take place from the cathode except from the area which is illuminated by the ultra-violet rays.

as an X -ray tube or in connection therewith, the focus of the reflecting cathode can be adjusted, if desired, in a manner similar to that. heretofore employed for adjusting the focus of a gas tube. While, therefore,

the focus is converging, it can be adjusted to be either fine, medium, or broad, according to requirements.

My method of producing cathode discharges diflers from the thermionic method in that I do not expose the anode to radia tion directly from a hot body, and do not necessarily have a heated body inthe vacuum tube. I thus accomplish the release of electrons entirely by means of light of relatively short wave length. These are true photo-ionicdischar es.

In my system the ischarge from the illuminated surface can be directed as -de-- sired; and discharges take place from the surface which is directly illuminated, and

" not from .any other surface.

Because of the many different "sources from which ultra-violet light is obtainable,

plie may be varied within wide limits.

hode to the anode, is-

recise form in which the light is sup- 1s commensurate with my claims.

I claim 1. An electrical vacuum device comprising an evacuated envelope, an anode and a cathode located therein, means for; subjecting said cathode to the action of ultra-violet rays, means for varying the intensity of said ultra-violet rays, and means for preventing electrons emitted from the surface of the cathode from falling upon any other part of the device, except the anode.

2. A device of the character described comprising a highly evacuated vessel, an

anti-cathode .and a cathode located within fvent the rays thereof from reaching said anti-cathode, and means for causing ultraviolet rays from said source to fall upon'the inner surface of said cathode, so as to set up a cathode ray discharge for the production of X-rays.

3. A device of the character described, for the product-ion of X-rays, comprising a hollow vessel evacuated to the highest possible degree, an anti-cathode and a cathode located within said vessel, said cathode being concave and being focused uponsaid anti-cathode, a source of ultra-violet light,

so located relatively to the cathode that ultra-violet rays from said source can fall In instanceswhere my device is employed upon the inner surface only ofthe cathode, mechanism for regulating the intensity of the -ultra-violet rays, means for energizing said. source of ultra-violet rays, and connections for subjecting said cathode and said an anti-cathode serving as a target, a cathode, a source of ultra-violet light for illuminating said cathode, and mechanism lo cated within the tube for preventing the ultra-violet light from reaching the anticathode.

5. In an X-raytube the combinationlof a vessel evacuated to an extreme degree, an

anode and a cathode located within said vessel, said anode serving as a target, a source of ult a-violet lightfor illuminating said cathod and a screening member located within said evacuated vessel for the purpose of preventing ultra-violet rays from the source of ultraviolet light from reaching said anode.

6. In adevice of the character described the'combination of a vessel evacuated to an extreme degree, a cathode, and an anticathode located within said vessel a source of ultra-violet lightjmounted within said vessel and favorably located therein for the purpose of throwing ultra-violet light upon said cathode, and a screening inemher located within said vessel and in proximity to said source of ultra-violet light for the purpose of preventing ultra-violet rays from reaching said anti-cathode.

7. In an X-ray apparatus the combination of a vessel evacuated to an extreme degree, a cathode and an anti-cathode located within said vessel, an electrically operated source of ultra-violet light located within said vessel. for the purpose of subjecting said cathode to the action of ultra-violet light, a transformer provided with a primary winding and with a plurality of secondary windings, connections from one of said secondary windings to said cathode and said anti-cathode for energizing the same, and connections from another of said secondary windings to said velectrically oper-. ated source of ultra-violet light, for the purpose of energizing the same.

8. In an X-ray apparatus the combination of a vessel evacuated to an extreme degree,

a cathode and an anti-cathode mounted within said vessel, the anti-cathode serving as atarget, an electrically operated source of ultra-violet light located within said vessel and disposed in close proximit to said cathode, a screening member locate between said source of ultra-violet light and said anti-cathode for the purpose of screening said anti-catl1ode from ultra-violet rays, a transformer provided with a primary winding Whereb'yrit may be energized, said transformer being further provided with a pair 0f secondary windings, connections from one of said secondary windings to said cathode and said anti-cathode for the purpose of causing a discharge to take place from said anti-cathode to said cathode, connection sfrom the other of said secondary windings to said electrically operated source of ultra-violet light, and condensers and a -pancake transformer included Within said last-mentioned connections.

ARTHUR MUTSCHELLER. 

